Index: wp-includes/js/autosave.dev.js
===================================================================
--- wp-includes/js/autosave.dev.js	(revision 13154)
+++ wp-includes/js/autosave.dev.js	(working copy)
@@ -3,6 +3,10 @@
 jQuery(document).ready( function($) {
 	var dotabkey = true;
 
+	if ( autosaveL10n.autosaveInterval <= 0 ) {
+		return false;
+	}
+
 	autosaveLast = $('#post #title').val() + $('#post #content').val();
 	autosavePeriodical = $.schedule({time: autosaveL10n.autosaveInterval * 1000, func: function() { autosave(); }, repeat: true, protect: true});